Würzburg, Universiẗat, Diss., 2005. / Erscheinungsjahr an der Haupttitelstelle: 2004.

Ziel dieser Arbeit war die Entwicklung einer allgemein anwendbaren Methode für die Simulation von ultraschnellen Prozessen und experimentellen Observablen. Hierfür wurden die Berechnung der elektronischen Struktur mit der zeitabhängigen Dichtefunktionaltheorie (TDDFT) und das Tully-Surface-Hopping-Verfahren für die nichtadiabatische Kerndynamik auf der Basis klassischer Trajektorien miteinander kombiniert. Insbesondere wurde eine Beschreibung der nichtadiabatischen Kopplungen für TDDFT entwickelt. Diese Methode wurde für die Simulation noch komplexerer Systeme durch die Tight-Binding-Näherung für TDDFT erweitert. Da die zeitaufgelöste Photoelektronenspektroskopie (TRPES) ein exzellentes experimentelles Verfahren für die Echtzeitbeobachtung von ultraschnellen Prozessen darstellt, wurde eine TDDFT-basierte Methode für die Simulation von TRPES entwickelt. Der Methode liegt die Idee zu Grunde, das System aus Kation und Photoelektron näherungsweise durch angeregte Zustände des neutralen Moleküls oberhalb der Ionisierungsgrenze zu beschreiben. Um diese Zustände mit TDDFT berechnen zu können wurde eine Beschreibung der Übergangsdipolmomente zwischen angeregten TDDFT-Zuständen entwickelt. Des Weiteren wurden Simulationen im Rahmen des Stieltjes-Imaging-Verfahrens, das eine Möglichkeit der Rekonstruktion des Photoelektronenspektrums aus den spektralen Momenten bietet, durchgeführt. Diese spektralen Momente wurden aus den diskreten TDDFT-Zuständen berechnet. Die breite Anwendbarkeit der entwickelten theoretischen Methoden für die Simulation von komplexen Systemen wurde an der Photoisomerisierung in Benzylidenanilin sowie der ultraschnellen Photodynamik in Furan, Pyrazin und mikrosolvatisiertem Adenin illustriert. Die dargestellten Beispiele demonstrieren, dass die nichtadiabatische Dynamik im Rahmen von TDDFT bzw. TDDFTB sehr gut für die Untersuchung und Interpretation der ultraschnellen photoinduzierten Prozesse in komplexen Molekülen geeignet ist. / The goal of this thesis was the development of a generally applicable theoretical framework for the simulation of ultrafast processes and experimental observables in complex molecular systems. For this purpose, a combination of the time-dependent density functional theory (TDDFT) for the description of the electronic structure with the Tully''s surface hopping procedure for the treatment of nonadiabatic nuclear dynamics based on classical trajectories was employed. In particular, a new approach for the calculation of nonadiabatic couplings within TDDFT was devised. The method was advanced for the description of more complex systems such as chromophores in a solvation shell by employing the tight binding approximation to TDDFT. Since the time-resolved photoelectron spectroscopy (TRPES) represents a powerful experimental technique for real-time observation of ultrafast processes, a TDDFT based approach for the simulation of TRPES was developed. The basic idea is the approximate representation of the combined system of cation and photoelectron by excited states of the neutral species above the ionization threshold. In order to calculate these states with TDDFT, a formulation of the transition dipole moments between excited states within TDDFT was devised. Moreover, simulations employing the Stieltjes imaging (SI) procedure were carried out providing the possibility to reconstruct photoelectron spectra from spectral moments. In this work, the spectral moments were calculated from discrete TDDFT states. The scope of the developed theoretical methods was illustrated on the photoisomerization in benzylideneaniline as well as on the ultrafast photodynamics in furan, pyrazine, and microsolvated adenine. The examples demonstrate that the nonadiabatic dynamics simulations based on TDDFT and TDDFTB are particularly suitable for the investigation and interpretation of ultrafast photoinduced processes in complex molecules.

Conselho Nacional de Desenvolvimento Científico e Tecnológico / Phenolic compouds and their derivatives constitute a leading family of natural compounds. Caffeic acid (CA) and caffeic acid phenethyl ester (CAPE) are the important members of phenolic compound, sharing several biological applications; antioxidant, neuroprotective, anti-inflammatory, antiproliferative, antibacterial, antiviral, antiatherosclerotic and anticancer properties. In spite of these, literature reportes some of its pro-oxidants activity depending on cellular environment. These pathophysiolocal properties increased the interest to evaluate the effect of CA and CAPE on the enzyme evolved in the purines salvage and the acetylcholine hydrolyzing enzyme the acetylcholineterase (AChE); in both PNS and CNS, since the essential constituent of our dietary items. Previously, our research group has reported that phenolic compound altered the activities of these enzymes. The AChE rapidly hydrolyzes the acetylcholine in neuronal and non neuronal tissues, mediating several neurodegenerative diseases. Beside the ACh, ATP (as co-neurotramittors) and adenosine are important signaling molecules, communicating cells in both PNS and CNS. In the extracellular signalling pathways; the adenine nucleotides, their derivative and the coupling of these molecules with specific receptor have a crucial role in nervous, vascular and immune systems. Once released, these molecules are hydrolyzed by a cascade of enzymes including ectonucleoside triphosphate diphosphohydrolase (NTPDase; E.C. 3.6.1.5, CD39), 5 -nucleotidase (E.C 3.1.3.5, CD73), ectonucleotide pyrophosphatase/phosphodiesterase (E-NPP), modulating crucially the signaling pathways in the normal functioning of nervous, vascular and immune systems. Next, adenosine deaminase (ADA) and xanthin oxidase (XO) degrade the adenosine and xanthine respectively which further control the functioning mechanisms in cellular events. Found in the neuronal and non neuronal (in both PNS and CNS) the AChE, NTPDase, 5'-nucleotidase, E-NPP, and ADA regulate several events including neurotransmission, inflammation, and thrombogenic process. We hypothesized to evaluate first the in vitro effects of CA on AChE activity in peripheral and central cholinergic system of rats. The results showed that CA significantly modulated the cholinergic system in vitro. By modulating the cholinergic system in vitro, apparently CA (e.g. phenolic structure) has proper role in neurotransmission. Therefore we hypothesizes to evaluate the in vivo effects of CA on AChE, NTPDase, E-NPP, 5'-nucleotidase, platelets aggregation and (ADA) in different tissues/cell from rats. The animals were treated during 30 days and killed after behavioral test. The results showed that caffeic acid increased significantly the AChE activity in hippocampus, hyphothalmus, pon and lymphocytes while that in cortex, cerebellum and striatum the AChE was inhibited. CA improves step-down latencies in the inhibitory avoidance. Investigating the in vivo effects of CA in purinergic system, caffecid acid increased the ATP and AMP hydrolysis in synaptosomes. However, in the synaptosomes no alterations were observed in the ADA activity in the groups evaluated in this study. CA increased the ATP and AMP hydrolysis, while the ADP hydrolysis was decreased in platelets. In the present findings caffeic acid decreased the platelets aggregation induced by ADP agonist. Treatment with CA also increased the NTPDase and ADA activities in lymphocytes of rats. Considering the dual function of caffeic acid in vitro and in vivo, the present study was extended to CAPE followed by acute treatment model (ip) in order to elucidate the effect of another phenolic structure on the same parameters. In this line the animals were treated (ip) with CAPE and killed after 40 minutes. In platelets, the results showed that the effect of CAPE increased the NTPDase, E-NPP, 5 -nucleotidase activities, while ADA activities did not change significantly. In synaptosomes CAPE significantly inhibited the NTPDase, and 5 -nucleotidase activity. CAPE induced no significant changes in ADA in synaptosomes but reduced XO in whole brain. Finaly we investigated the activity of AChE in cortex, cerebellum, striatum, hippocampus, hyphotalamus, pon, lymphocytes and muscules of rats treated with CAPE. The results showed that CAPE significantly decreased the AChE activity in cortex cerebellum and striatum. CAPE significantly increased the AChE activity in hippocampus hypothalamus, pons, muscle and lymphocytes. In cholinergic system our results clearly demonstrating that both compound with dual functions.These findings demonstrated that the AChE activities and the cascade of ecto-enzymes was alter in different tissues after treatment with CA and CAPE in rats, suggesting that these compound should be considered a potentially therapeutic agent in immune, vascular and neurological disorders related with the cholinergic purinergic system. / Os compostos fenólicos e seus derivados constituem uma importante família de compostos naturais. O ácido cafeico (AC) e o éster fenetil do ácido cafeico (CAPE) são membros importantes dessa família e compartilham algumas aplicações biológicas, tais como: antioxidante, neuroprotetor, antiinflamatório, antiproliferativo, antibacteriano, antiviral, antiaterosclerótico e anticancerígeno. Entretanto, a literatura relata algumas atividades pró-oxidantes, dependendo do ambiente celular. Devido a estas propriedades patofisiológicas, aumentou o interesse com o objetivo de avaliar o efeito de CA e CAPE sob as atividades das enzimas purinérgicas e da acetilcolinesterase (AChE), tanto no Sistema Nervoso Periférico (SNP) como no Sistema Nervoso Central (SNC). Previamente, nosso grupo de pesquisa relatou que o composto fenólico tem a capacidade de alterar as atividades dessas enzimas. A AChE rapidamente hidrolisa a acetilcolina (ACh) em tecidos neuronais e não neuronais, mediando algumas doenças neurodegenerativas. Ao lado da ACh, o ATP (como coneurotransmissor) e adenosina são importantes moléculas sinalizadoras, comunicando as células em ambos os SNP e do SNC. Nas vias de sinalização extracelulares, os nucleotídeos de adenina e seus derivados podem ser acoplados a receptores específicos e desse modo ter um papel crucial no sistema nervoso, sistema vascular e imune. Uma vez liberadas, estas moléculas são hidrolisadas por uma cascata de enzimas incluindo a ectonucleosídeo trifosfato difosfoidrolase (NTPDase; EC 3.6.1.5, CD39), 5'- nucleotidase (EC 3.1.3.5, CD73), ectonucleotideo pirofosfatase/fosfodiesterase (E-NPP), modulando definitivamente as vias de sinalização do funcionamento normal do sistema nervoso, sistema vascular e imune. Além disso, a adenosina deaminase (ADA) e a xantina oxidase (XO) degradam a adenosina e a xantina, respectivamente, as quais controlam o funcionamento de mecanismos em eventos celulares. As enzimas encontradas em tecidos neuronais e não neuronais como a AChE, a NTPDase, a 5'-nucleotidase, a E-NPP e a ADA regulam eventos celulares incluindo a neurotransmissão, inflamação e processos trombogênicos. Com essas informações, nós introduzimos a hipótese de avaliar primeiramente os efeitos in vitro de CA na atividade da AChE periférica e no sistema central colinérgico de ratos. Os resultados demonstraram que o CA modula significativamente o sistema colinérgico no estudo in vitro. Essa modulação demonstra aparentemente que o CA (estrutura fenólica) possui propriedades de ação que altera a neurotransmissão. Portanto, a hipótese de se avaliar os efeitos in vivo de CA na atividade da AChE, NTPDase, E-NPP, 5'-nucleotidase, ADA e da agregação de plaquetas em diferentes tecidos de ratos tornou-se evidente. Para esse estudo, os animais foram tratados durante 30 dias e sacrificados após o teste comportamental. Os resultados do experimento demonstraram que o CA aumentou significativamente a atividade da AChE em hipocampo, hipotálamo, ponte e nos linfócitos, enquanto que no córtex cerebral, cerebelo e estriado a AChE foi inibida. No teste comportamental o CA teve evolução de melhora na latência de passos da esquiva inibitória. A investigação dos efeitos in vivo do CA no sistema purinérgico demonstrou aumento na hidrólise de ATP e AMP em sinaptossomas. Entretanto, não foram observadas alterações significativas na atividade da ADA em sinaptossomas dos grupos avaliados neste estudo. Em plaquetas, o CA aumentou significativamente a hidrólise de ATP e AMP, enquanto que a hidrólise de ADP foi diminuída nesse tecido. No presente estudo o CA reduziu significativamente a agregação de plaquetas induzida pelo agonista ADP. Além disso, o tratamento com CA aumentou significativamente as atividades da NTPDase e da ADA em linfócitos de ratos. Considerando a dupla função de CA, in vitro e in vivo, o presente estudo foi estendido para CAPE seguindo o modelo de tratamento agudo pela via intraperitoneal (ip) com o objetivo de elucidar o efeito de uma segunda estrutura fenólica sobre os mesmos parâmetros. Nesta linha de pesquisa, os animais foram tratados ip com CAPE e eutanasiados após 40 minutos. Em plaquetas, os resultados demonstraram que o CAPE aumentou significativamente a atividade da NTPDase, E-NPP e 5'-nucleotidase, enquanto que a atividade da ADA não foi alterada significativamente. Em sinaptossomas, o CAPE inibiu significativamente a atividade da NTPDase e da 5'-nucleotidase. O CAPE não induziu alterações significativas na atividade da ADA em sinaptossomas, mas reduziu significativamente a atividade da XO em todo o cérebro. Finalmente, nós investigamos a atividade da AChE no córtex cerebral, cerebelo, estriado, hipocampo, hipotálamo, ponte, linfócitos e músculos de ratos tratados com CAPE. Os resultados demonstraram que CAPE diminuiu significativamente a atividade da AChE em córtex cerebral, cerebelo e estriado. O CAPE aumentou significativamente a atividade da AChE em hipotálamo, hipocampo, ponte, músculo e linfócitos. No sistema colinérgico, nossos resultados demonstram claramente que ambos os compostos possuem dupla função. Estes resultados demonstram que as atividades da AChE e da cascata das ecto-enzimas foram alteradas em diferentes tecidos após o tratamento com CA ou CAPE em ratos, sugerindo que estes compostos devem ser considerados agentes com potencial terapêutico em doenças imunes, vasculares e neurológicas relacionadas com o sistema colinérgico e purinérgico.